1. Field of the Invention
The present invention relates to packaging thin flexible materials and more particularly to packaging flexible sheet materials in stacks to prevent movement of the individual sheets relative to one another and render said sheets safe from vibrational and impact damage and contamination in transit and/or storage.
2. Description of the Prior Art
Flexible magnetic disks are widely used in the computer industry for recording magnetic data. Such disks are also commonly referred to as "floppy disks." Flexible disks have a thickness of approximately 0.003 inches and a diameter of approximately eight inches. During actual use in a disk drive, the disks are placed in a jacket to protect the disk and provide structural support. Prior to placing said flexible disks into the plastic jacket which completely surrounds the media, the disks are extremely vulnerable to damage. Though damage can be very slight and invisible to the naked eye, it can cause serious magnetic defects in the media. Damage to the media can be in the form of physical distortion rendering the center hole oblong or creasing the edges and/or contamination.
The tendency toward damage has effectively prevented the shipment of flexible disks except when said flexible disks are placed within the plastic jacket. Though placing the flexible media within the plastic jacket protects the media, it is not an acceptable solution on a practical basis. If the media is placed within the jacket merely for the purposes of shipment, the individual placement of a flexible disk within the cartridge is an expensive process. It consumes considerable time, requires large numbers of jackets and large packages to ship large quantities. Also, the media can be damaged during the procedure in which it is inserted into the jacket and removed therefrom.
Attempts have been made to ship unburnished flexible magnetic media, but said attempts have met with limited success. In the prior art a stack of flexible disks has been loaded upon a mandrel where the mandrel has been adapted for the center hole geometry of the media. Suitable end washers hold the disks at each end of the stack. This assembly, with mandrel and end washers in place, has then been placed in a carton and used for the purposes of shipment. However, it has been found that accelerations experienced during the shipping process cause center hole damage to the flexible media due to the engagement of the mandrel. As the geometry of the center hole is extremely critical for accurate positioning of the media on a flexible disk drive, shipping flexible media upon a solid mandrel has been found to be an unacceptable procedure. In the final analysis, there has not been a practical solution to the problem of shipping flexible mangetic media which is economical, prevents relative translation and rotation between the media, and protects the media from handling damage and particulate contamination.